Re: [PATCH 3/3] hw/cxl: Add Physical Port Control (Opcode 5102h)

[Arpit Kumar <arpit1.kumar@samsung.com>]

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On 10/06/25 03:45PM, Jonathan Cameron wrote:
>On Mon,  2 Jun 2025 19:29:42 +0530
>Arpit Kumar <arpit1.kumar@samsung.com> wrote:
>
>
>Very interesting to see support for this. It will enable a load
>of additional test cases.
>
>> added assert-deassert PERST implementation, reset PPB
>> for physical port.
>Added
okay
>
>Please also include some details of testing done and what happens.
>Given I know we have some issues with reset that we haven't resolved
>I'm curious if you see them here.
>
sure, I have tested this command using libcxl-mi. will share the details in the
next iteration (V2) of the patch series.
>>
>> Signed-off-by: Arpit Kumar <arpit1.kumar@samsung.com>
>
>> +/* Assert - Deassert PERST */
>> +#define ASSERT_WAIT_TIME_MS 100
>> +
>>  /* link state flags */
>>  #define LINK_STATE_FLAG_LANE_REVERSED    (1 << 0)
>>  #define LINK_STATE_FLAG_PERST_ASSERTED   (1 << 1)
>> @@ -662,6 +666,114 @@ static CXLRetCode cmd_get_physical_port_state(const struct cxl_cmd *cmd,
>>      return CXL_MBOX_SUCCESS;
>>  }
>>
>> +static struct PCIDevice *cxl_find_port_dev(uint8_t ppb_id, PCIBus *bus)
>> +{
>> +    PCIDevice *d;
>> +    int devfn;
>> +
>> +    for (devfn = 0; devfn < ARRAY_SIZE(bus->devices); devfn++) {
>
>As in patch one, maybe use the for_each_pci_...  Though with the callback
>needed it may end up slightly more complex that this.
>
right, will use the same.
>
>> +        d = bus->devices[devfn];
>> +        if (d) {
>> +            if (object_dynamic_cast(OBJECT(d), TYPE_CXL_DSP)) {
>> +                uint8_t port = PCIE_PORT(d)->port;
>I'd not bother with the local variable for this one.
>
okay
>                 if (PCIE_PORT(d)->port == ppb_id) {
>                     return d;
>                 }
>
>> +                if (port == ppb_id) {
>> +                    return d;
>> +                }
>> +            }
>> +        }
>> +    }
>> +    return NULL;
>> +}
>> +
>> +static CXLRetCode deassert_PERST(Object *obj, ResetType type, uint8_t pn, CXLCCI *cci)
>> +{
>> +    ResettableClass *rc = RESETTABLE_GET_CLASS(obj);
>> +    ResettableState *s = rc->get_state(obj);
>> +
>> +    if (cci->pports.perst[pn].issued_assert_PERST) {
>> +        if (cci->pports.perst[pn].asrt_time == -1 && !s->hold_phase_pending) {
>
>I'd flip the logic as then can return early in error case and reduce
>indent of the rest.
>
okay, will update in V2.
>
>> +            qemu_mutex_lock(&cci->pports.perst[pn].lock);
>
>            QEMU_LOCK_GUARD(&cci->pports.prst[pn].lock);
>
>> +            resettable_release_reset(obj, type);
>> +            cci->pports.perst[pn].issued_assert_PERST = false;
>> +            cci->pports.pport_info[pn].link_state_flags &=
>> +                ~LINK_STATE_FLAG_PERST_ASSERTED;
>> +            cci->pports.perst[pn].asrt_time = ASSERT_WAIT_TIME_MS;
>> +            qemu_mutex_unlock(&cci->pports.perst[pn].lock);
>and drop explicit unlock.
got it
>> +        } else {
>> +            return CXL_MBOX_INTERNAL_ERROR;
>> +        }
>> +    } else {
>> +        return CXL_MBOX_INTERNAL_ERROR;
>> +    }
>> +    return CXL_MBOX_SUCCESS;
>> +}
>> +
>> +static CXLRetCode assert_PERST(Object *obj, ResetType type, uint8_t pn, CXLCCI *cci)
>> +{
>> +    ResettableClass *rc = RESETTABLE_GET_CLASS(ocpgs@samsung.combj);
>> +    ResettableState *s = rc->get_state(obj);
>> +
>> +    if (cci->pports.perst[pn].issued_assert_PERST || s->exit_phase_in_progress) {
>> +        return CXL_MBOX_INTERNAL_ERROR;
>> +    }
>> +
>
>WITH_QEMU_LOCK_GUARD() perhaps
okay
>
>> +    qemu_mutex_lock(&cci->pports.perst[pn].lock);
>> +    cci->pports.perst[pn].issued_assert_PERST = true;
>> +    cci->pports.pport_info[pn].link_state_flags |=
>> +        LINK_STATE_FLAG_PERST_ASSERTED;
>> +    resettable_assert_reset(obj, type);
>> +    qemu_mutex_unlock(&cci->pports.perst[pn].lock);
>> +
>> +    /* holding reset phase for 100ms */
>> +    while (cci->pports.perst[pn].asrt_time--) {
>> +        usleep(1000);
>Is this happening synchronously?  I'd kind of expect it to be a background thing
>where we'd just check it had finished.
okay, will update it in V2 of patch series.
>> +    }
>> +    return CXL_MBOX_SUCCESS;
>> +}
>> +
>> +/*CXL r3.2 Section 7.6.7.1.3: Get Physical Port Control (Opcode 5102h)*/
>> +static CXLRetCode cmd_physical_port_control(const struct cxl_cmd *cmd,
>> +                                            uint8_t *payload_in,
>> +                                            size_t len_in,
>> +                                            uint8_t *payload_out,
>> +                                            size_t *len_out,
>> +                                            CXLCCI *cci)
>> +{
>> +    PCIBus *bus = &PCI_BRIDGE(cci->d)->sec_bus;
>> +    PCIDevice *dev;
>> +    struct cxl_fmapi_get_physical_port_control_req_pl {
>> +        uint8_t PPB_ID;
>> +        uint8_t Ports_Op;
>> +    } QEMU_PACKED *in;
>> +
>> +    in = (struct cxl_fmapi_get_physical_port_control_req_pl *)payload_in;
>
>Often we cheat on these where the type is locally defined and do
>
>    struct cxl_fmapi_get_physical_port_control_req_pl {
>        uint8_t ppb_id;
>        uint8_t ports_op;
>    } QEMU_PACKED *in = (void *)payload_in;
>
>Given it's all together the type isn't confusing or ambiguous even
>though we use a void * instead of the more specific cast.
>
>Note also that it is better to stick to local style and use lower_case
>style for structure element naming etc.
>
got it
>> +
>> +    if (len_in < sizeof(*in)) {
>> +        return CXL_MBOX_INVALID_PAYLOAD_LENGTH;
>> +    }
>> +
>> +    uint8_t pn = in->PPB_ID;
>> +    dev = cxl_find_port_dev(pn, bus);
>> +    if (!dev) {
>> +        return CXL_MBOX_INTERNAL_ERROR;
>> +    }
>> +
>> +    switch (in->Ports_Op) {
>> +    case 0:
>> +        assert_PERST(OBJECT(&dev->qdev), RESET_TYPE_COLD, pn, cci);
>
>Even for these probably
>
>assert_perst()
>
okay
>> +        break;
>return CXL_MBOX_SUCESS;
>> +    case 1:
>> +        deassert_PERST(OBJECT(&dev->qdev), RESET_TYPE_COLD, pn, cci);
>> +        break;
>> +    case 2:
>> +        device_cold_reset(&dev->qdev);
>> +        break;
>> +    default:
>> +        return CXL_MBOX_INVALID_INPUT;
>> +    }
>> +    return CXL_MBOX_SUCCESS;
>> +}
>> +
>
>> @@ -3878,4 +3995,15 @@ void cxl_initialize_usp_mctpcci(CXLCCI *cci, DeviceState *d, DeviceState *intf,
>>      cci->intf = intf;
>>      cxl_init_cci(cci, payload_max);
>>      cxl_set_phy_port_info(cci); /* store port info */
>> +    /* physical port control */
>> +    for (int i = 0; i < PCI_DEVFN_MAX; i++) {
>> +        qemu_mutex_init(&cci->pports.perst[i].lock);
>
>perst is definitely port wise - not linked to CCI so that stuff should be
>in the port structures themselves.
>
>> +        cci->pports.perst[i].issued_assert_PERST = false;
>> +        /* Assert PERST involves physical port to be in
>wrap at 80 chars.
okay
>> +         * hold reset phase for minimum 100ms. No other calls
>> +         * are entertained until Deassert PERST command.
>> +         * https://patchwork.ozlabs.org/project/linux-pci/patch/20190523194409.17718-1-niklas.cassel@linaro.org/#2178369
>
>Blocking other commands is fine but we should lock up emulation of other stuff
>in the system and I think you currently do.
>
got it. I think you meant 'we should *not lock up..'
>> +         */
>> +        cci->pports.perst[i].asrt_time = ASSERT_WAIT_TIME_MS;
>> +    }
>>  }
>> diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
>> index 9eb128a1e8..f877d60b39 100644
>> --- a/include/hw/cxl/cxl_device.h
>> +++ b/include/hw/cxl/cxl_device.h
>> @@ -146,10 +146,18 @@ struct cxl_phy_port_info {
>>      uint8_t supported_ld_count;
>>  } QEMU_PACKED;
>>
>> +/* assert-deassert PERST */
>> +struct pperst {
>> +    bool issued_assert_PERST;
>> +    int asrt_time;
>> +    QemuMutex lock;
>> +};
>> +
>>  struct phy_port {
>>      uint8_t num_ports;
>>      uint8_t active_port_bitmask[0x20];
>>      struct cxl_phy_port_info pport_info[PCI_DEVFN_MAX];
>> +    struct pperst perst[PCI_DEVFN_MAX];
>>  };
>>
>>  /* CXL r3.1 Table 8-34: Command Return Codes */
>

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